1. Field of the Invention
The present invention relates to a structure for an optical device and method of fabricating the same and, more specifically, to a structure for an optical device, which includes a light scattering layer for producing nanoparticles to scatter light, and method of fabricating the same.
2. Discussion of Related Art
A junction, which is associated with an essential technique for the configuration of an electronic circuit in semiconductor fabrication technologies, has actively been developed for several dozens of years. The junction may be mainly categorized into a pnp or npn junction, which is applied to a bipolar transistor in which signals are amplified by electron/s and holes, a Josephson junction, which is formed of superconductor-metal (insulator)-superconductor, and the likes.
A trilayer Josephson junction using YBCO is introduced by B. H. Moeckly [“All Y—Ba—Cu—O c-axis trilayer interface-engineered Josephson junctions”, Appl. Phys. Lett., Vol. 78, pp.790-792, 2001]. According to B. H. Moeckly, a lower YBCO thin layer is deposited on a LaAlO3 substrate, and the surface of the lower YBCO thin layer is modified using Ar plasma. Thereafter, an upper YBCO thin layer is deposited in vacuum, thereby forming a trilayer Josephson junction. However, the complicated oxide structure of the resultant YBCO Josephson junction is highly sensitive to the amount of doped oxygen. For this reason, when the YBCO Josephson junction is used in the fabrication of highly integrated circuits, it is difficult to obtain uniform and reproducible junctions.
In other words, the use of conventional pnp or npn junctions or Josephson junctions precludes the implementation of highly integrated electronic circuits owing to the sensitiveness of a stoichiometric ratio caused by compound oxide materials.
In recent years, extensive studies have been made of the amplification of signals in optical fibers based on an optical nonlinear effect. However, in order to elevate the sensitivity of an amplifier, it is necessary to increase a distance between optical fibers as well as the length of the optical fibers. As a result, the amplifier needs to be fabricated to a larger size so that it cannot be easily applied to the highly integrated electronic circuits.
Meanwhile, a technique of accumulating or amplifying surface plasmons, i.e., optical signals using a light scattering layer for producing nanoparticles is proposed by J. Tominaga et al. [“Local plasmon photonic transistor”, Appl. Phys. Lett., Vol. 78, pp.2417-2419, 2001]. In this technique, when low-power laser or heat is irradiated on the light scattering layer to produce nanoparticles, surface plasmons are accumulated according to a variation in the transmissivity of the nanoparticles. Also, when the transmissivity of the nanoparticles is varied by controlling the power of laser or heat, the accumulated surface plasmons are externally scattered so that an optical amplification effect can be achieved.
J. Tominaga et al. discloses a thin film transistor, which includes a protective layer, a light scattering layer, and a protective layer. The light scattering layer is formed of AgOx, and each protective layer is formed of ZnS—SiO2. In this structure, surface plasmons are amplified about 60 times as much as conventional bipolar transistors by using a red light laser having a power of 1.5 to 3.5 mW. However, the above-described structure allows oxygen and nitrogen to leak out from the light scattering layer during the generation of the nanoparticles, thus crystalline mismatch occurs.